Conventionally, as a flat panel display, a liquid crystal display apparatus which uses a liquid crystal molecule as a shutter has been mainly used. In recent years, as a display apparatus which achieves further ultra-thinness and expanded display size, a self-emitting type display apparatus using an organic EL device has attracted attention.
The display apparatus using an organic EL device has a structure in which plural devices including an electrode (anode) in the shape of a stripe that is made up of a transparent conductive film; an electrode (cathode) in the shape of a stripe that is made up of a metallic thin film, and is orthogonal to the anode; and an organic EL layer formed between these electrodes are provided on a transparent substrate. The anodes and the cathodes are arranged in the shape of a matrix, and the respective intersecting portions of the anodes and the cathodes each correspond to a pixel. By applying a prescribed driving voltage between prescribed electrodes, a prescribed pixel can be caused to emit light.
Such an organic EL device, unlike the liquid crystal device utilizing liquid crystal molecules sandwiched between two substrates as a shutter, is of self-emitting type, and thus offers various advantages, such as that it has a high visibility; does not have viewing angle dependence; allows use of a film substrate having flexibility; is thin and lightweight, compared to the liquid crystal display apparatus; and the like.
On the other hand, because of using organic matter, the organic EL device easily reacts with moisture, oxygen, and the like, which can result in degradation of the characteristics thereof. In other words, when the organic EL layer reacts with moisture and oxygen in the air to cause corrosion and oxidation, the degraded portion becomes a non-light-emitting part (a dark spot), resulting in the light-emitting function of the device being lost. Therefore, it is necessary to take various measures for protecting the organic EL device against the surrounding air.
Examples of prior art documents disclosing such a measure include patent document 1 (Japanese Patent Application Laid-Open No. 10-012385), the patent document 2 (Japanese Patent Application Laid-Open No. 2002-025765), patent document 3 (Japanese Patent Application Laid-Open No. 2003-017244), and patent document 4 (Japanese Patent Application Laid-Open No. 2003-086359).
In the patent document 1, a display apparatus in which an organic EL device is sealed with a glass plate or a metallic plate is proposed. However, in this method, the thickness and weight of the glass plate cancels the feature of thin and lightweight structure of the organic EL device.
In addition, in the patent documents 2 to 4, a display apparatus having a thin-type structure in which a resin film for stress relaxation and an inorganic film for protection against the surrounding air are laminated on the organic EL device, and in which the organic EL device is sealed by these laminated films, is proposed. However, as an inorganic film which is provided for the purpose of protection against the surrounding air, a material, such as a silicon oxide film, a silicon nitride film, a silicon nitride-oxide film, or the like, which is inferior in flexibility to the resin film, is generally used. Therefore, when stresses are concentrated on this layer, a crack is generated in some cases. For example, when the entire display apparatus including the substrate on which the organic EL device is formed is bent, stresses are most concentrated on the substrate surface, and thus, stresses are concentrated on the inorganic film which is located on the surface, resulting in a rupture. Such a crack in the inorganic film causes the sealing function to be lost, resulting in the organic EL device being degraded. In addition, the resin film provided in the layer under the inorganic film has a high moisture permeability and moisture-holding ability, as compared to the inorganic film, and thus, the resin film adjacent to the organic EL device may cause the organic EL device to be degraded.
In addition, as is stated in the patent document 3, for example, it can be supposed that, by repeatedly laminating plural resin films and plural inorganic films, the moisture resistance is improved. However, with a structure in which plural resin films and plural of inorganic films are repeatedly laminated, the number of manufacturing processes is increased, and the manufacturing cost is increased.
The present invention relates to a display apparatus using an organic EL device and a manufacturing method therefor, and a purpose of the present invention is to provide a structure of a display apparatus that provides the organic EL device with high protection against the surrounding air and high flexibility, and manufacturing method for a display apparatus that can realize such a structure by a simple process at low cost.